Wireless communications systems are widely used to enable mobile connectivity. That is, users may employ wireless devices to access various communication networks while on the move, either in a vehicle or on foot. There are many wireless access technologies, such as frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA) that may be used to enable simultaneous wireless connectivity within a shared frequency band.
In one example, a wireless device employed by a mobile user is known as an access terminal (AT). The AT facilitates communication with other users through a wireless access technology to an access network (AN). In general, the AN is in turn connected to other communication networks, such as the Public Switched Telephony Network (PSTN), a Public Switched Data Network (PSDN), the Internet, private networks, etc. For example, the AN serves as the portal to other networks for the mobile user. In one example, the mobile user connects to a telephone call via the PSTN. In another example, the mobile user connects to Internet service providers, computer databases, data servers, etc. via the Internet. The wireless access communication link from the AN to the AT is known as a forward link. In the opposite direction, the wireless access communication link from the AT to the AN is known as a reverse link. In one example, the AN includes pilot signals within the forward link. Pilot signals are known reference signals (without user traffic) sent by a transmitter to assist the receiver in acquiring, tracking, and communicating on a link. For example, the pilot signals sent by a transmitter may be used by the receiver for channel estimation, time synchronization, frequency referencing, phase referencing, code referencing, etc. The receiver may receive the pilot signals and, for example, measure its signal strength to estimate the propagation channel characteristics over the receive frequency band. Such information may be used, for example, in equalizing the propagation channel characteristics to improve overall performance.
For certain wireless access technologies, a set of pilot signals is affiliated within a scheduler group. In addition, an instance of the Quick NAK (QN) protocol, which is part of the radio link layer, is associated with the scheduler group. A new QN instance is created whenever a new scheduler group appears or is created. In the example when all existing active set members of a given scheduler group are deleted from the scheduler group and disjoint pilot signals from the same scheduler group are assigned to an AT, the AT will create a new scheduler group and hence a new QN instance. On the other hand, the AN will typically in this case continue to use the same QN instance. Consequently, there's a mismatch between the QN instance of the AT (which is new) and the QN instance of the AN (which is old). Thus, the first data packet received over the QN instance (i.e., new at the AT and old at the AN) will cause the generation of a negative acknowledgement (NAK) message from the AT with the leading edge not set and indicating the trailing edge. The NAK message will result in the AN requiring a retransmission of the data packet for up to the NAK Abort interval time period.